The field of the present invention is oil well completion tools and techniques.
Wells are conventionally drilled through production zones with casings installed to adjacent the production zones. Such casings may extend through certain production zones where multiple zones exist. In such cases, the casings may be strategically placed or later perforated to provide access to additional zones. Typically a casing does not extend to the bottom of unconsolidated sand in the production zone of the well as drilled. In sandy conditions, the bottom of the well may fill in before completion. Under many circumstances, a liner is to be placed in the well with perforations at the productive zones. Additionally, gravel packing about the liner is common.
Upon the completion of such wells, sand control adapters are frequently employed to seal the joints between the upper ends of the liners and the casings. Such devices prevent sand from being entrained into the production. One such adapter is illustrated in U.S. Pat. No. 5,052,483, the disclosure of which is incorporated herein by reference.
For well completion, it is frequently necessary to clear out the bottom of the hole, insert an appropriate liner, gravel pack the production zone or zones and seal the liner off at the casing. Multiple trips down a well are frequently required to accomplish each of these tasks. The pulling of tools is, of course, expensive. Mechanisms have been designed for accomplishing a variety of tasks with one trip down the well. U.S. Pat. No. 5,425,423, the disclosure of which is incorporated herein by reference, illustrates a well tool which can drill, under ream and gravel pack with one trip down the well. U.S. Pat. No. 5,497,840, the disclosure of which is incorporated herein by reference, discloses another completion system for drilling in, placing and hanging a liner, cementing portions of the well and providing a seal between the casing and the liner. This may be accomplished with one trip down the well. Of course all systems allow for retraction of the drill string. Some equipment may be sacrificed in the well.
The present invention is directed to well completion, minimizing trips down the well. A well may be lined, the liner locked in place, the production zone or zones gravel packed, the well cleaned and the equipment removed, all with a single trip.
Accordingly, it is an object of the present invention to provide improved well completion methods. Other and further objects and advantages will appear hereinafter.